The impacts of urbanization on emissions and air quality: comparison of four visions of Austin, Texas

The impacts of alternative regional development patterns on emissions, dry deposition, and air quality were examined using four visions of future land use in Austin, Texas associated with a doubling of the population in 20-40 years from 2001. Emissions and their spatial allocation were determined based on the development pattern and used to predict hourly ozone concentrations. Differences in hourly ozone concentrations due to changes in anthropogenic emissions between the future case scenarios and a 2007 base case ranged from -14 to 22 ppb and were primarily associated with the implementation of federal mobile source standards; differences due to biogenic emissions and dry deposition due to urbanization ranged from only -1.4 to 0.7 ppb. These differences in the magnitude of emissions produced greater changes in air quality than differences in regional development patterns between the four scenarios. Differences in hourly ozone concentrations between the future development scenarios and a 2007 base case ranged from -14 to 22 ppb, in contrast to differences of -3 to 5 ppb between the future scenarios. The results imply that although the effects of urbanization patterns are non-negligible, the pattern of urban development is not as significant as reductions in emissions per capita.     

Simulation of air quality impacts from prescribed fires on an urban area

On February 28, 2007, a severe smoke event caused by prescribed forest fires occurred in Atlanta, GA. Later smoke events in the southeastern metropolitan areas of the United States caused by the Georgia-Florida wild forest fires further magnified the significance of forest fire emissions and the benefits of being able to accurately predict such occurrences. By using preburning information, we utilize an operational forecasting system to simulate the potential air quality impacts from two large February 28th fires. Our "forecast" predicts that the scheduled prescribed fires would have resulted in over 1 million Atlanta residents being potentially exposed to fine particle matter (PM2.5) levels of 35 microg m(-3) or higher from 4 p.m. to midnight. The simulated peak 1 h PM2.5 concentration is about 121 microg m(-3). Our study suggests that the current air quality forecasting technology can be a useful tool for helping the management of fire activities to protect public health. With postburning information, our "hindcast" predictions improved significantly on timing and location and slightly on peak values. "Hindcast" simulations also indicated that additional isoprenoid emissions from pine species temporarily triggered by the fire could induce rapid ozone and secondary organic aerosol formation during late winter. Results from this study suggest that fire induced biogenic volatile organic compounds emissions missing from current fire emissions estimate should be included in the future.     

Reformulated and alternative fuels: modeled impacts on regional air quality with special emphasis on surface ozone concentration

The comprehensive European Air Pollution and Dispersion model system was used to estimate the impacts of the usage of reformulated and alternative fuels on regional air quality with special emphasis on surface ozone concentrations. A severe western European summer smog episode in July 1994 has been used as a reference, and the model predictions have been evaluated for this episode. A forecast simulation for the year 2005 (TREND) has been performed, including the future emission development based on the current legislation and technologies available. The results of the scenario TREND are used as a baseline for the other 2005 fuel scenarios, including fuel reformulation, fuel sulfur content, and compressed natural gas (CNG) as an alternative fuel. Compared to the year 1994, significant reductions in episode peak ozone concentrations and ozone grid hours are predicted for the TREND scenario. These reductions are even more pronounced within the investigated alternative and reformulated fuel scenarios. Especially, low sulfur fuels are appropriate for an immediate improvement in air quality, because they effect the emissions of the whole fleet. Furthermore, the simulation results indicate that the introduction of CNG vehicles would also enhance air quality with respect to ozone.     

Photochemical fate of carbamazepine in surface freshwaters: laboratory measures and modeling

It is shown here that carbamazepine (CBZ) would undergo direct photolysis and reaction with (?)OH as the main phototransformation pathways in surface waters. Environmental lifetimes are expected to vary from a few weeks to several months, and predictions are in good agreement with available field data. Acridine (I) and 10,11-dihydro-10,11-trans-dihydroxy-CBZ (V) are the main quantified phototransformation intermediates upon direct photolysis and (?)OH reaction, respectively. The photochemical yield of mutagenic I from CBZ is in the 3-3.5% range, and it is similar for both direct photolysis and (?)OH reaction: it would undergo limited variation with environmental conditions. In contrast, the yield of V would vary in the 4-8.5% range depending on the conditions, because V is formed from CBZ by (?)OH (9.0% yield) more effectively than upon direct photolysis (1.4% yield). Other important photointermediates, mostly formed from CBZ upon (?)OH reaction, are an aromatic-ring-dihydroxylated CBZ (VI) and N,N-bis(2-carboxyphenyl)urea (VII). Compounds VI and VII are formed by photochemistry and are not reported as human metabolites; thus, they could be used as tracers of CBZ phototransformation in surface waters. Interestingly, VI has recently been detected in river water.     

Climate impacts of air quality policy: switching to a natural gas-fueled public transportation system in New Delhi

Between 2001 and 2003, public transport vehicles in New Delhi were required to switch their fuel to natural gas in an attemptto reduce their air pollution impacts. This study examines the climatic impacts of New Delhi's fuel switching policy, and outlines implications for such efforts in rapidly industrializing countries. Natural gas is mostly composed of methane, an important greenhouse gas. Emitted aerosols (black carbon, particulate organic carbon, and sulfate) also cause radiative forcing. We find that methane and black carbon emissions are critical contributors to the change in carbon dioxide equivalent [CO2(e)] emissions. In New Delhi, the switch to natural gas results in a 30% increase in CO2(e) when the impact of aerosols is not considered. However, when aerosol emissions are taken into account in our model, the net effect of the switch is estimated to be a 10% reduction in CO2(e), and there may be as much as a 30% reduction in CO2(e). There is significant potential for emissions reductions through the United Nations Framework Convention on Climate Change (UNFCCC) Clean Development Mechanism for such fuel switching projects.     

Regional air quality: local and interstate impacts of NO(x) and SO2 emissions on ozone and fine particulate matter in the eastern United States

While the U.S. air quality management system is largely designed and managed on a state level, many critical air quality problems are now recognized as regional. In particular, concentrations of two secondary pollutants, ozone and particulate matter, are often above regulated levels and can be dependent on emissions from upwind states. Here, impacts of statewide emissions on concentrations of local and downwind states' ozone and fine particulate matter are simulated for three seasonal periods in the eastern United States using a regional Eulerian photochemical model. Impacts of ground level NO(x) (e.g., mobile and area sources), elevated NO(x) (e.g., power plants and large industrial sources), and SO2 emissions are examined. An average of 77% of each state's ozone and PM(2.5) concentrations that are sensitive to the emissions evaluated here are found to be caused by emissions from other states. Delaware, Maryland, New Jersey, Virginia, Kentucky, and West Virginia are shown to have high concentrations of ozone and PM(2.5) caused by interstate emissions. When weighted by population, New York receives increased interstate contributions to these pollutants and contributions to ozone from local emissions are generally higher. When accounting for emission rates, combined states from the western side of the modeling domain and individual states such as Illinois, Tennessee, Indiana, Kentucky, and Georgia are major contributors to interstate ozone. Ohio, Indiana, Tennessee, Kentucky, and Illinois are the major contributors to interstate PM(2.5). When accounting for an equivalent mass of emissions, Tennessee, Kentucky, West Virginia, Virginia, and Alabama contribute large fractions of these pollutants to other states.     

Synthetic glucocorticoids in the environment: first results on their potential impacts on fish

Human pharmaceuticals have been shown to be entering the aquatic environment in quantities that may produce adverse effects to aquatic organisms. This paper investigates the impacts of synthetic glucocorticoids (GCs), which are used in large amounts as anti-inflammatory drugs, on fish. Mammalian cell lines were transiently transfected with trout corticosteroid receptors (GR1, GR2, and MR) and the transactivation abilities of ten of the most prescribed GCs in the UK were measured in vitro. They showed significantly higher activity with GR2 than with GR1. In order to assess any impacts in vivo, adult fathead minnows were exposed to either 1 μg prednisolone/L or 1 μg beclomethasone dipropionate/L for 21 days. Plasma glucose concentrations were increased and leucocytes were reduced significantly in GC-exposed groups compared to the control group. In another experiment, fish were exposed to three different concentrations of Beclomethasone dipropionate and a dose-dependent increase of plasma glucose was found. The results suggest that low concentrations of synthetic GCs present in water could cause adverse effects on fish. Therefore, quantification of GCs in the aquatic environment and the effects of GCs at environmentally relevant concentrations are required in order to determine if GCs pose a threat to wild fish populations.     

Propagation of uncertainty in hourly utility NOx emissions through a photochemical grid air quality model: a case study for the Charlotte, NC, modeling domain

One of the major hypothesized sources of uncertainties in air quality model inputs is the emission inventory. A probabilistic hourly NOx emission inventory for 32 units of nine coal-fired power plants in the Charlotte domain for the year 1995 was propagated through the Multiscale Air Quality Simulation Platform (MAQSIP). The inventory was developed using time series techniques. Time series for a 4-d episode were simulated and propagated through the air quality model 50 times in order to represent the ranges of uncertainty in hourly emissions and predicted ozone levels. Intra-unit autocorrelation in emissions and inter-unit dependence were accounted for. The range of uncertainty in predicted ozone was greater when inter-unit dependence was included as compared to when units were treated as statistically independent. Uncertainties in maximum ozone hourly or 8-h concentrations at a specific location could be attributed to a specific power plant based upon regression analysis. Out of 3969 grid cells in the modeling domain, there were 43 and 1654 grid cells with a probability greater than 0.9 of exceeding a 1-h 120 ppb standard and an 8-h 80 ppb standard, respectively. The time series of predicted ozone values had similar autocorrelation as compared to monitored data. The implications of these results for air quality management are addressed.     

Regional characterization of freshwater Use in LCA: modeling direct impacts on human health

Life cycle assessment (LCA) is a methodology that quantifies potential environmental impacts for comparative purposes in a decision-making context. While potential environmental impacts from pollutant emissions into water are characterized in LCA, impacts from water unavailability are not yet fully quantified. Water use can make the resource unavailable to other users by displacement or quality degradation. A reduction in water availability to human users can potentially affect human health. If financial resources are available, there can be adaptations that may, in turn, shift the environmental burdens to other life cycle stages and impact categories. This paper proposes a model to evaluate these potential impacts in an LCA context. It considers the water that is withdrawn and released, its quality and scarcity in order to evaluate the loss of functionality associated with water uses. Regionalized results are presented for impacts on human health for two modeling approaches regarding affected users, including or not domestic uses, and expressed in disability-adjusted life years (DALY). A consumption and quality based scarcity indicator is also proposed as a midpoint. An illustrative example is presented for the production of corrugated board with different effluents, demonstrating the importance of considering quality, process effluents and the difference between the modeling approaches.     

Ventilation effects on air quality and on the yield and quality of ewe milk in winter

The effects of ventilation on air quality, and on the welfare and production performance of dairy ewes were assessed in a 6-wk trial conducted during the winter of 2002. Thirty-six midlactation Comisana ewes were divided into three groups of 12, which were randomly balanced for parity, time of lambing, and number of lambs suckled. Treatments were low (LOV), moderate (MOV), and programmed ventilation regimen (PROV). In LOV and MOV rooms, fans provided 10 ventilation cycles of 40 min each at a fan speed of 1 and 2 m/s, respectively. In the PROV room, the fan was programmed to maintain a 70% relative humidity. Mean ventilation rates were 23, 47, and 73 m3/h per ewe in LOV, MOV, and PROV rooms, respectively. Air concentrations of microorganisms and dust, and of gaseous pollutants were measured twice weekly. Cell-mediated immune response to phytohemagglutinin at d 1, 21 and 42, and humoral response to chicken egg albumin at d 11, 21, 30, and 40 were determined. At d 39, ewes were injected with 2 IU of porcine adreno-corticotropic-hormone/kg body weight(0.75), and subjected to blood sampling for evaluation of cortisol concentrations immediately before and 1, 2, and 4 h after adreno-corticotrophic-hormone injection. Milk yield was recorded daily. Individual milk samples were analyzed weekly for composition, renneting parameters, and somatic cell count. The LOV treatment resulted in higher air concentrations of NH3 and CO2 than the MOV and PROV treatments. Greater amounts of total and respirable dust were found in the PROV room than in the LOV and the MOV rooms. The LOV ewes had lower milk yield than the PROV ewes, lower milk casein content, and higher rate of clot formation than the MOV and PROV ewes. The ventilation regimen did not affect the immune and endocrine responses of the ewes. Results suggest that an intermittent ventilation regimen, providing a mean ventilation rate of 47 m3/h per ewe at a fan speed of 2 m/s, is required to sustain the yield and cheese-making ability of ewe milk during the winter season.     

FTIR kinetic, product, and modeling study of the OH-initiated oxidation of 1-butanol in air

A kinetic and product study was performed on the reaction of OH radicals with 1-butanol in a 480 L indoor photoreactor and also in the EUPHORE outdoor smog chamber in Valencia, Spain. Long path in situ FTIR spectroscopy and gas chromatography with photoionization detection were used to analyze reactants and products. Using a kinetic relative rate technique, a rate coefficient of k(OH + 1-butanol) = (8.28 +/- 0.85) x 10(-12) cm3 s(-1) was measured in 740 Torr synthetic air at 298 +/- 2 K. The reaction products observed and their fractional molar yields were (in percent) butanal (51.8 +/- 7.1), propanal (23.4 +/- 3.5), ethanal (12.7 +/- 2.2), and formaldehyde (43.4 +/- 2.4). In addition, the results support the probable formation of 4-hydroxy-2-butanone. Propanal, ethanal, and formaldehyde could also be formed in secondary reactions of some of the primary aldehydic products. However, under the conditions employed in the experiments, the contribution from secondary reactions is very minor. On the basis of the product studies, a detailed atmospheric degradation mechanism was constructed and tested against experimental data by chemical box model calculations. Measured and simulated concentration-time profiles for selected reactants were in excellent agreement.     

Impact of fuel quality regulation and speed reductions on shipping emissions: implications for climate and air quality

Atmospheric emissions of gas and particulate matter from a large ocean-going container vessel were sampled as it slowed and switched from high-sulfur to low-sulfur fuel as it transited into regulated coastal waters of California. Reduction in emission factors (EFs) of sulfur dioxide (SO?), particulate matter, particulate sulfate and cloud condensation nuclei were substantial (≥ 90%). EFs for particulate organic matter decreased by 70%. Black carbon (BC) EFs were reduced by 41%. When the measured emission reductions, brought about by compliance with the California fuel quality regulation and participation in the vessel speed reduction (VSR) program, are placed in a broader context, warming from reductions in the indirect effect of SO? would dominate any radiative changes due to the emissions changes. Within regulated waters absolute emission reductions exceed 88% for almost all measured gas and particle phase species. The analysis presented provides direct estimations of the emissions reductions that can be realized by California fuel quality regulation and VSR program, in addition to providing new information relevant to potential health and climate impact of reduced fuel sulfur content, fuel quality and vessel speed reductions.     

Climate changes and potential impacts on postharvest quality of fruit and vegetable crops: A review

Temperature increase and the effects of greenhouse gases are among the most important issues associated with climate change. Studies have shown that the production and quality of fresh fruit and vegetable crops can be directly and indirectly affected by high temperatures and exposure to elevated levels of carbon dioxide and ozone. Temperature increase affects photosynthesis directly, causing alterations in sugars, organic acids, and flavonoids contents, firmness and antioxidant activity. Carbon dioxide accumulation in the atmosphere has directly effects on postharvest quality causing tuber malformation, occurrence of common scab, and changes in reducing sugars contents on potatoes. High concentrations of atmospheric ozone can potentially cause reduction in the photosynthetic process, growth and biomass accumulation. Ozone-enriched atmospheres increased vitamin C content and decreased emissions of volatile esters on strawberries. Tomatoes exposed to ozone concentrations ranging from 0.005 to 1.0 μmol/mol had a transient increase in β-carotene, lutein and lycopene contents.     

Area of influence (AOI) development: fast generation of receptor-oriented sensitivity fields for use in regional air quality modeling

An approach is developed and tested to extend discrete, source-based sensitivity results to provide a complete set of information for source-air quality impacts, including inversion of those results to develop receptor-oriented source-impact sensitivities. First, the decoupled direct sensitivity analysis method in 3D (DDM-3D) is used to calculate a finite number of forward sensitivities from discrete points. These results are then interpolated using tessellation to provide complete fields of forward, emissions-based sensitivities, i.e., how emissions in any one grid cell within the domain impact any other cell. Receptor-oriented sensitivities are then found by inverting the set of forward sensitivities and can be used to identify the area of influence (AOI). This economically provides results similar to what would be found using an adjoint model. The present approach is computationally less intensive than adjoint modeling for a large number of receptors, and provides both source-oriented and receptor-oriented pollutant response fields that can be used for air quality management and health impact analyses. The forward sensitivity interpolation procedure, as well as the receptor-oriented sensitivities, is evaluated using data withholding.     

Air quality impacts of climate mitigation: UK policy and passenger vehicle choice

In 2001-2002 the UK began taxing vehicles according to CO2 emission rates. Since then, there has been a significant increase in consumer choice of small cars and diesel engines. We estimate CO2 reductions and air quality impacts resulting from UK consumers switching from petrol to diesel cars from 2001 to 2020. Annual reductions of 0.4 megatons (Mt) of CO2 and 1 million barrels of oil are estimated from switching to diesels. However, diesels emit higher levels of particulate matter estimated to result in 90 deaths annually (range 20-300). We estimate 570, 460, and 0 additional deaths per Mt of CO2 abated, for Euro III, Euro IV, and post-Euro IV emission class vehicles, respectively. CO2 policies are suspected to have contributed substantially to diesel growth, but the magnitude of impact has yet to be quantified rigorously. To the extent that CO2 policies contribute to diesel growth, coordinating CO2 controls with tightening of emission standards would save lives. This research shows that climate policy, while reducing fuel use and CO2, does not always ensure ancillary health benefits. Lessons from the UK can help inform policies designed elsewhere which strive to balance near-term ambient air quality and health with long-term climate mitigation.     

A risk modeling framework to evaluate the impacts of climate change and adaptation on food and water safety

Climate change may be a factor leading to increased risks of food- and waterborne illnesses from consumption of existing and emerging biological hazards. It is beneficial to develop integrated approaches to evaluate, and provide scientific assessments of, potential climate change adaptation measures to inform risk management related to climate and weather events. To this end, a risk modeling framework was created to facilitate estimations of the impact of weather and climate change on public health risks from biological hazards in food and water and to compare potential adaptation and risk mitigation strategies. The framework integrates knowledge synthesis methods, data storage and maintenance, and stochastic modeling. Risk assessment models were developed for food and water safety case studies for demonstrative purposes. Scenario analyses indicated that implementing intervention measures to adapt to changing climate impacts might mitigate future public health risks from pathogens to varying degrees. The framework brings a generic approach to allow for comparison of relative public health risks and potential adaptation strategies across hazards, exposure pathways, and regions to assist with preventive efforts and decision-making.     

非洲芝麻及其芝麻油品质的研究

对非洲芝麻样品组成成分及芝麻油的品质进行了分析。结果表明:非洲芝麻中脂肪含量最高的为Rakai 23芝麻,粗蛋白含量最高的为Agou 86芝麻,草酸含量最少的为Agou86芝麻,灰分含量最少的为Dossou 3芝麻,千粒重最重的为San 54芝麻;非洲芝麻压榨芝麻油酸价整体偏高,过氧化值整体偏低,碘值最高的为Rakai 23芝麻油,折光指数和皂化值差别不大;非洲芝麻油脂肪酸组成基本一致,不饱和脂肪酸含量最高的为Rakai 23芝麻油;非洲芝麻油木脂素类物质含量最多的为San 54芝麻油,维生素E含量最高的为Agou 86芝麻油。     

Combined radio frequency-vacuum and hot air drying of kiwifruits: Effect on drying uniformity,energy efficiency and product quality

Two drying methods, both individually and in their combination [RF-vacuum drying (RFVD), hot air drying (HAD) and RFVD+HAD] were evaluated for three-layer drying of 6 mm thick kiwifruit slices in order to shorten drying time, improve energy efficiency and product quality. An electrode gap of 95 mm and vacuum of 20.1 kPa were selected for RFVD applications based on previous studies. Results showed that the total drying time was the shortest (480 min) when using RFVD, followed by RFVD+HAD (600 min; 20% longer) and HAD (900 min, almost double). However, non-uniform drying patterns were observed in both RFVD and HAD methods, but the RFVD+HAD process resulted in a more uniform moisture distribution both within and among the fruit slices. The average energy efficiency of HAD was improved remarkably from 9.92% to 22.93% by applying the RFVD+HAD method. Additionally, the RFVD+HAD process resulted in better product quality attributes like color, shrinkage ratio and rehydration capacity. Therefore, the RFVD+HAD method is recommended as a time and energy efficient drying technology for kiwifruits with a better moisture distribution and product quality.